These investigations evaluate the impact of myocardial ischemia on cardiac performance and metabolism in hypertrophied hearts, neonatal hearts, and patients undergoing cardiac operations. Special attention is focused in adult hearts on the right ventricle. Neonatal studies examine effects of ischemia on both ventricles. Methods are assessed wherein ischemic injury may be ameliorated, recovery enhanced or the injured ventricle supported to minimize ischemic injury. Enhanced understanding of the mechanisms by which ischemic injury occurs in these classes of ventricles should provide better techniques for protecting hearts during operations. Survival should be improved and quality of heart function enhanced. Attempts are made to define independently performance of heart chambers as pumps compared with intrinsic muscle properties. Sonomicrometric techniques allow continuous measurement of chamber dimensions. Combined with intracavitary pressure measurements, myocardial function is divided into abnormalities of diastolic properties and abnormalities of systolic performance. Systolic performance is generally expressed as stroke work per increment of end-diastolic length. Diastolic properties are expressed as the relationship between myocardial wall stress and strain. Myocardial biochemistry is correlated with abnormalities in systolic and diastolic performance and analyzed from the adenine nucleotide high energy phosphate pool, mitochondrial and sarcoplasmic reticulum function and myofibrillar ATPase activity. Left ventricular hypertrophy is produced by selective obliteration of one leaflet of the aortic valve in puppies; right ventricular hypertrophy is produced by pulmonary artery banding in young animals. The efficacy of specific myocardial protective techniques is assessed using these systems. In particular, coronary sinus retroperfusion to protect myocardium in the hypertrophied and nonhypertrophied state is examined. Isolated right ventricular injury is created using differential myocardial cooling and ventricular interaction is studied. Studies in patients use pressure-dimension analyses to define right ventricular injury and recovery.
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